December 2016

Sinkholes. What are they and why are they becoming more common?

A sinkhole occurs when there is a depression or crater on the earth's surface caused by a collapse. They often vary in size, anywhere from 1 to 600 meters deep and wide. Sinkholes not only vary in size but also vary from soil covered dips to hard-edged chasms cut into the bedrock. Sinkholes are not confined to any particular area of the planet, and occur due to massive earthquakes across Latin America such as the one in Guatemala in 2010, to the small depressions in my home country of the United Kingdom, which happened very recently in Newcastle. Sinkholes have even been found on the surface of the famous 67P asteroid, often called Churyumov–Gerasimenko.

Daniel Junor
Projects Abroad Volunteer
Wales Powys – United Kingdom


Photo by: Casa Presidencial/Handout/REUTERS /
www.cbsnews.com/pictures/giant-sinkholes/

Sinkholes can be split up into three different categories: (i) solution, (ii) subsidence, and (iii) collapse sinkholes. Solution and subsidence sinkholes are very similar, as both are caused by surface water weathering away at the soluble bedrock; subsidence sinkholes differ as they have a layer of soil or sediment above the bedrock. Collapse sinkholes, while also caused by weathering from surface water, create cavities, as more surface water weathers away the roof, which becomes too thin to hold up the weight of the surface, collapsing into the cavity. Collapse sinkholes are the most hazardous ones as they are more often instantaneous, meaning more people are at risk of being killed, which is worrying as they are becoming more common.

There has been a steep rise in the number of collapse sinkholes resulting from human activity. Collapses of old mines and salt domes are a major problem, especially in the United States, most famously the Daisetta in 2008.

However, most commonly, water mains burst or there is a collapse in an old sewer system. These are highly dangerous as they are in urban areas and more likely to have a larger impact on human lives. Bolivia itself currently does not have any major sinkholes. However, thanks to over mining, there is an increasing risk. The Cerro Rico Mountain is perhaps the most famous mountain in Bolivia and even appears on its national flag, but due to years of mining for its natural silver reserves it has started to hollow out. The constant tunnels dug into the mountain for mining have become unstable; a 700-square meter sinkhole appeared at its summit. Precautions were obviously taken to deal with this matter; the Bolivian government implemented a $2.4 million dollar plan to fill in the sinkhole. The stabilization project involves a mixture of cement, polyethylene, and sand layered with metal nets supported by arches within the mountain.


Photo by: robertkaplinsky.com/work/sink-hole/

Sinkholes have existed for thousands of years and as such have acquired quite a few local names. In the Bahamas and the surrounding area, they are called "black holes" and "blue holes." The black holes are found in the Bahamas, most notably on the South Andros Island, where they can reach a depth up to 181 meters. They are formed by chemical erosion and called black holes on account of the one meter surface that is darkened by toxic bacteria. A blue hole, on the other hand, is a water filled sinkhole, most commonly found in the ocean with a different deep blue color. The deepest blue hole in the world is found in the Bahamas and is called Dean's Blue Hole. It reaches 202 meters in depth and, while technically not the deepest blue hole, it is the deepest of the blue holes in the ocean.

Sinkholes have existed for thousands of years and as such have acquired quite a few local names. In the Bahamas and the surrounding area, they are called "black holes" and "blue holes." The black holes are found in the Bahamas, most notably on the South Andros Island, where they can reach a depth up to 181 meters. They are formed by chemical erosion and called black holes on account of the one meter surface that is darkened by toxic bacteria. A blue hole, on the other hand, is a water filled sinkhole, most commonly found in the ocean with a different deep blue color. The deepest blue hole in the world is found in the Bahamas and is called Dean's Blue Hole. It reaches 202 meters in depth and, while technically not the deepest blue hole, it is the deepest of the blue holes in the ocean.


Photo by Daniel LeClair/REUTERS /
www.cbsnews.com/pictures/giant-sinkholes/

Cenotes

Cenotes are often used to describe the sinkholes on the Yucatán peninsula, Belize, and other areas in Central America. Cenotes are sinkholes where the limestone bedrock has collapsed revealing the groundwater underneath. They played an important role in Mayan culture as they provided water sources for their cities. The cenotes were sacred to the Mayans and later exploration found in them gold and human skeletons used as sacrifices. The term cenote is derived from the Yucatan Maya term ts'onot, which describes a location with accessible groundwater.

Also used in Mexico is the term sótanos, with the most famous one being the Sótano de las Golondrias, or the "Cave of Swallows" located in San Luis Potosí.

In China, there are the giant sinkholes known as tiankengs, which translated directly into English means "heavenly pit." The tiankengs are vast. In fact, the largest sinkhole in the world is the Xiaozhai Tiankeng, which measures 626 meters long by 537 meters wide. Also interesting about the Xiaozhai Tiankeng is that it is a double nested sinkhole. It first reaches 320 meters deep, with a second hole within measuring 342 meters in depth.


Photo by Kyodo News via AP Photo /
www.abcnews.go.com/topics/news/disasters/sinkholes.htm

The world has seen some awe inspiring and terrifying sinkholes throughout the years. One of the most disturbing sinkholes is the Berezniki sinkhole in the Russian Urals. What is different about this sinkhole is that it continues to grow to this day. Originally appearing in 1986, the sinkhole has now grown to be 200 meters deep, 80 meters long, and 40 meters wide. Also worrying is that Berezniki produces 10% of the world's potash supply, which is a main ingredient in fertilizers, amongst other things, and the sinkhole threatens the only rail access to the city. The true cause of the sinkhole remains unclear. Many suggest that it could have been caused by the abandoned mines that litter the district. More terrifying was the sinkhole that appeared in Guatemala City in 2010, swallowing a threestory factory and sinking 30 meters. The sinkhole had a number of different causes. First, sewage leakage from poor quality underground piping had eroded away the volcanic pumice upon which Guatemala City is built. Adding to the strain on the pipes was the increased rainfall from tropical storm Agatha on May 30th. It was not just the added rainfall the culprit, as three days earlier the Pacaya volcano 40 kilometers south of Guatemala City erupted. This had a devastating effect when the rainfall increased as the underground pipes became clogged with soot.


Photo by expatior.com/ik-kil-cenote-gobsmacking-and-brain-popping/

Florida saw one of the most devastating sinkholes in 1994 when a sinkhole collapsed beneath an 80 million ton gypsum stack. The sinkhole was most likely caused by a collapse in the limestone beneath, but its erosion was certainly aided by the acidic water runoff from the gypsum stack. What was most devastating about the Gypsum stack sinkhole was its toxic chemicals contaminating the underground water and consequently 90% of Florida's drinking water.

Less terrifying yet more stunning are the Sarisarinama holes in Venezuela's Bolivar state. The most famous one is the Sima Humboldt, most notable for its gigantic size: 352 meters wide, 314 meters deep, with its width expanding to 502 meters at its base. Most amazing about the Sima Humboldt is that due to its vast size it contains a different ecosystem from that of the jungle above it.

Who was Simon Patiño, the Industrialist and Entrepreneur
SIMON PATIÑO was born in the department of Cochabamba in 1860, from very humble beginnings, his parents being of Spanish and Indian origin. Little is known of his early life, only that he began working in a general store and later drove mule trains in the Bolivian mountains.
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